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Biomedical subjects

Rudolf Fahlbusch

Publications and source records attributed to Rudolf Fahlbusch.

At least 37 records · Page 2Linked to original sources
PubMed2005

Prolonged oral hydroxyurea and concurrent 3d-conformal radiation in patients with progressive or recurrent meningioma: results of a pilot study.

PURPOSE: Treatment of recurrent and progressive meningiomas remains a challenge in clinical neurooncology. This study was designed to evaluate the efficacy of the simultaneous application of 3d-conformal radiotherapy and chemotherapy with hydroxyurea (HU). PATIENTS AND METHODS: Twenty-one patients with recurrent or progressive meningiomas (13 benign, 4 atypical and malignant, 4 with unproven histology) received treatment by fractionated 3d-conformal radiation (55.8-59.4 Gy) and concurrent HU, administered for a median time of three months with a daily dosage of 20 mg/kg. Response was evaluated using clinical and neuro-imaging data. RESULTS: Disease stabilization was achieved in 14/21 patients (pts). Three pts had significant improvement of tumor associated neurological symptoms with imaging criteria of minor response. Progression free survival rates 1 year and 2 years after the initiation of radio-chemotherapy were 84% and 77%, respectively. At the time of analysis a total of 6/21 pts presented with progressive disease with a median time to progression of 59 weeks. Documented radio- and chemotherapy associated toxicity was minimal; only one patient discontinued HU treatment due to gastrointestinal symptoms such as anorexia and weight loss. CONCLUSION: Results obtained in this study indicate that treatment with HU and simultaneous radiotherapy is safe and effective with disease stabilization in the majority of patients. Randomized trials comparing radiosurgery versus radiochemotherapy versus fractionated radiotherapy are warranted.

Administration, Oral↗
PubMed2005

Comparing 0.2 tesla with 1.5 tesla intraoperative magnetic resonance imaging analysis of setup, workflow, and efficiency.

RATIONALE AND OBJECTIVES: To compare low-field with high-field intraoperative magnetic resonance imaging (MRI) in respect to setup, workflow, and efficiency. MATERIALS AND METHODS: A total of 750 patients were investigated either with a 0.2 T (March 1996-July 2001) or a 1.5 T (April 2002-August 2004) MRI system adapted for intraoperative use. RESULTS: With the low-field setup, 330 patients were examined in 65 months; with the high-field setup, 420 patients were examined in 29 months, which is a 2.8-fold increase in cases per month (14.5 versus 5.1) reflecting improved ease of use. Concerning intraoperative workflow, the time for preparation to start intraoperative imaging decreased fivefold (2 minutes instead of 10 minutes); navigation was applied more often with 57% versus 51% (240/420 versus 167/330), whereas functional data were integrated in 35% versus 39% (84/240 versus 65/167). Application of navigation updates was doubled (22% versus 11%; 53/240 versus 18/167). Image acquisition time was reduced by a factor of two, allowing a more detailed imaging protocol, whereas the image quality is clearly improved in the high-field setup, where there was no difference between the standard preoperative image quality compared with the intraoperative quality. This contributed to an increased detection of tumor remnants and extended resections in pituitary (36% versus 29%; 47/129 versus 17/59) and glioma surgery (41% versus 26%; 38/93 versus 28/106). CONCLUSION: Compared with the low-field setup, the high-field setup results not only in clearly superior image quality and increased imaging armamentarium, contributing to increased rates of detected tumor remnants, but also in a distinct improvement of intraoperative workflow. Furthermore, intraoperative high-field MRI offers various modalities beyond standard anatomic imaging, such as magnetic resonance spectroscopy, diffusion tensor imaging, and functional MRI.

Brain Diseases↗
PubMed2005

1.5 T: intraoperative imaging beyond standard anatomic imaging.

Intraoperative high-field MRI with integrated microscope-based neuronavigation is a safe and reliable technique providing immediate intraoperative quality control. Major indications are pituitary tumor, glioma, and epilepsy surgery. Intraoperative high-field MRI provides intraoperative anatomic images at high quality that are up to the standard of pre- and postoperative neuroradiologic imaging. Compared with previous low-field MRI systems used for intraoperative imaging, not only is the image quality is clearly superior but the imaging spectrum is much wider and the intraoperative work flow is improved. Furthermore, high-field MRI offers various modalities beyond standard anatomic imaging, such as magnetic resonance spectroscopy, diffusion tensor imaging, and functional MRI.

Brain Diseases↗
PubMed2005

Suberoylanilide hydroxamic acid (SAHA) has potent anti-glioma properties in vitro, ex vivo and in vivo.

Current treatment modalities for malignant gliomas do not allow long-term survival. Here, we identify suberoylanilide hydroxamic acid (SAHA), an inhibitor of histone deacetylases (HDAC), as an effective experimental anti-glioma agent. Administration of SAHA to various glioma cell lines obtained from human, rat and mouse inhibited tumour cell growth in a range of 1-10 microm. This anti-glioma property is associated with up-regulation of the cell cycle control protein p21/WAF, as well as the induction of apoptosis. A novel tumour invasion model using slice cultures of rat brain corroborated the anti-glioma properties of SAHA in the organotypic brain environment. In this model, glioma invasion compromised adjacent brain parenchyma, and this tumour-associated cytotoxicity could be inhibited by SAHA. In addition, a 10-fold dose escalation experiment did not challenge the viability of cultured brain slices. In vivo, a single intratumoural injection of SAHA 7 days after orthotopic implantation of glioma cells in syngeneic rats doubled their survival time. These observations identify chromatin-modifying enzymes as possible and promising targets for the pharmacotherapy of malignant gliomas.

Acetylation↗
PubMed2005

Preoperative and intraoperative diffusion tensor imaging-based fiber tracking in glioma surgery.

OBJECTIVE: To investigate the intraoperative displacement of major white matter tracts during glioma resection by comparing preoperative and intraoperative diffusion tensor imaging-based fiber tracking. METHODS: In 37 patients undergoing glioma surgery, preoperative and intraoperative diffusion tensor imaging was performed with a 1.5-T magnetic resonance scanner applying an echo-planar imaging sequence with six diffusion directions. For three-dimensional tractography, we implemented a knowledge-based multiple-region-of-interest approach applying user-defined seed regions in the color-coded maps of fractional anisotropy. Tracking was initiated in both the retrograde and orthograde directions according to the direction of the principal eigenvector in each voxel of the region of interest. The tractography results were also assigned color, applying the convention used in color-coded fractional anisotropy maps. RESULTS: Preoperative and intraoperative fiber tracking was technically feasible in all patients. Fiber tract visualization gave a quick and intuitive overview of the displaced course of white matter tracts in three-dimensional space. Comparison of preoperative and intraoperative tractography depicted a marked shifting of major white matter tracts during glioma removal. Maximum white matter tract shifting ranged from -8 to +15 mm (+2.7 +/- 6.0 mm; mean +/- standard deviation); in 29.7%, an inward and in 62.2%, an outward shifting was detected. CONCLUSION: Comparing preoperative and intraoperative fiber tracking visualizes a marked shifting and deformation of major white matter tracts because of tumor removal. This shifting emphasizes the need for an intraoperative update of navigation systems during resection of deep-seated tumor portions near eloquent brain areas. Fiber tracking is a method not only for preoperative neurosurgical visualization but also for further intraoperative planning.

Adolescent↗
PubMed2005

Proton magnetic resonance spectroscopic imaging integrated into image-guided surgery: correlation to standard magnetic resonance imaging and tumor cell density.

OBJECTIVE: In this study, we attempted to improve the delineation of the infiltration zone in gliomas using proton magnetic resonance spectroscopic imaging (1H MRSI). In conventional magnetic resonance imaging (MRI), the boundaries of gliomas sometimes are underestimated. 1H MRSI is a noninvasive tool that can be used to investigate the spatial distribution of metabolic changes in brain lesions. The purpose was to correlate tumor cell density from histopathological specimens with metabolic levels and the coregistered metabolic maps. METHODS: We developed a method to integrate spectroscopic data depicted as metabolic maps of biochemically pathological tissue into frameless stereotaxy. In seven patients harboring gliomas, we performed 1H MRSI with high spatial resolution and evaluated the spectral data. An algorithm was developed for user-independent calculation of pathological voxels and for visualization as metabolic maps. These maps were integrated into a three-dimensional MRI data set used for frameless stereotaxy. Stereotactic biopsies were taken from three different areas in and around the tumor involving the maximum pathological change, the border zone, and an area from outside the spectroscopically suspicious area. These specimens were correlated to the exact voxel positions in the stereotactic image space and evaluated histopathologically. RESULTS: In all cases, the implementation of the metabolic maps into frameless stereotaxy was successful, and stereotactic biopsies were acquired by use of the spectral data. A relation could be demonstrated between the metabolic changes and tumor cell density ranging from 60 to 100% in the maximum pathological area to 5 to 15% in the border zone. Interestingly, the tumor areas defined by the metabolic maps and histopathologically confirmed by biopsy exceeded the T2-weighted signal change in all cases, ranging from 6 to 32% in the examined volume. CONCLUSION: Our preliminary data suggest that 1H MRSI may be useful in combination with frameless stereotaxy to define more exactly the tumor infiltration zone in glioma surgery compared with conventional anatomic MRI alone.

Algorithms↗
PubMed2005

The outcome of surgery in 668 patients with acromegaly using current criteria of biochemical 'cure'.

BACKGROUND AND AIM: The aim of this study was to illustrate the present role of transsphenoidal surgery as primary therapy in GH-secreting adenomas, and to compare the results concerning control of disease with previous series using older criteria of cure. METHOD: We report on a consecutive series of 688 acromegalic patients treated over a time period of 19 years. Biochemical cure was defined as normalisation of basal GH level, suppression of GH levels to below 1 ng/ml during an oral glucose load and normalisation of IGF-I levels. Of the 506 patients undergoing primary transsphenoidal surgery, a total of 57.3% postoperatively fulfilled the criteria used. RESULTS: The rate of biochemical 'cure' correlated with the magnitude of the initial GH levels, the tumour size and invasion. The overall complication rate was below 2%. Mortality in this series was 0.1% (1 of 688). During a follow-up period of 10.7 years only two recurrences (0.4%) occurred. However, in the patients treated by transcranial surgery and by repeat surgery the cure rate was found to be relatively low (5.2 and 21.3% respectively). CONCLUSIONS: These data suggest that surgery remains with very few exceptions the primary treatment of acromegaly for (i) a high cure rate, (ii) low morbidity, (iii) low recurrence rate and (iv) immediate decline of GH. Based on current criteria of cure, recurrences are uncommon. However, cure by surgery alone is improbable in patients harbouring extended, invasive tumours with high secretory activity, in whom further adjuvant treatment is mandatory.

Acromegaly↗
PubMed2005

Transsphenoidal surgery in acromegaly investigated by intraoperative high-field magnetic resonance imaging.

OBJECTIVE: The aim of the study was to evaluate the effect of intraoperative high-field (1.5 Tesla) magnetic resonance imaging (MRI) on the results of transsphenoidal surgery of GH-secreting pituitary macroadenomas. METHODS: Twenty-three acromegalic patients (mean tumor size, 25 +/- 12 mm; untreated preoperative GH, 4.2-159 microg/l; IGF-I, 349-1111 microg/l) were investigated by intraoperative high-field MRI. If intraoperative imaging depicted an accessible tumor remnant, resection was continued. RESULTS: In five patients intraoperative MRI led to further tumor removal, two of these met the consensus criteria for endocrine remission after 3 months. In two patients basal GH and oral glucose tolerance test (OGTT) were <2 microg/l, only IGF-I was slightly elevated, and in one patient GH was <5 microg/l and OGTT was 2 microg/l, with elevated IGF-I. Final intraoperative MRI showed no tumor remnants in 14 patients; eight of them met the consensus criteria for remission of acromegaly. In the patients with MRI showing incomplete removal (four suspect findings and five patients with intended partial removal) none was normalized. CONCLUSION: With regard to the patients with a tumor configuration in whom complete tumor removal was considered (n = 18), intraoperative MRI increased the rate of endocrine normalization from 33 to 44% applying the consensus criteria, and improved endocrine outcome to 'nearly normalization' in another 17%. With regard to preoperative GH levels and tumor size, intraoperative MRI can help to achieve endocrine remission in patients who are normally considered not to be curable. However, taking GH as the tumor marker, even intraoperative high-field MRI was not able to detect tumor remnants in every case.

Acromegaly↗
PubMed2005

Malignant glioma-induced neuronal cell death in an organotypic glioma invasion model. Technical note.

Rapid growth and diffuse brain infiltration are hallmarks of malignant gliomas. The underlying molecular pathomechanisms of these tumors, however, remain to be determined. The authors present a novel glioma invasion model that allows researchers to monitor consecutively tumor cell proliferation and migration in an organotypic brain environment. Enhanced green fluorescent protein-labeled F98 rat glioma cells were implanted into slice cultures obtained from a rat hippocampus, and tumor growth was microscopically documented up to 20 days in vitro. Invasion along radially oriented migratory streams could be observed 5 days after implantation of rat F98, human U87MG, and mouse GL261 glioma cells, whereas human Be(2)c neuroblastoma cells and mouse HT22 hippocampal neurons failed to invade the brain parenchyma. Following implantation of F98 glioma cells into the entorhinal cortex, cell death was observed within the infiltrated brain parenchyma as well as in the neuroanatomically connected dentate gyrus. Application of the N-methyl-D-aspartate receptor antagonist MK801 to the culture medium significantly reduced neuronal degeneration in the dentate gyrus, whereas the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor antagonist GYKI 52466 inhibited peritumoral cytotoxicity. This new model allows researchers to address in a systematic manner the molecular pathways of brain invasion as well as specific tumor-host interactions such as necrosis.

Animals↗
PubMed2004

Intraoperative diffusion-tensor MR imaging: shifting of white matter tracts during neurosurgical procedures--initial experience.

PURPOSE: To prospectively evaluate the location of white matter tracts with diffusion-tensor imaging (DTI) during neurosurgical procedures. MATERIALS AND METHODS: Ethical committee approval and signed informed consent were obtained. A 1.5-T magnetic resonance imager with an adapted rotating surgical table that is placed in a radiofrequency-shielded operating theater was used for pre- and intraoperative imaging. DTI was performed by applying an echo-planar imaging sequence with six diffusion directions in 38 patients (20 female patients, 18 male patients; age range, 7-77 years; mean age, 45.6 years) who were undergoing surgery (35 craniotomy and three burr hole procedures). Color-encoded maps of fractional anisotropy were generated by depicting white matter tracts. A rigid registration algorithm was used to compare pre- and intraoperative images. RESULTS: Intraoperative DTI was technically feasible in all patients, and no major image distortions occurred in the areas of interest. Pre- and intraoperative color-encoded maps of fractional anisotropy could be registered; these maps depicted marked and highly variable shifting of white matter tracts during neurosurgical procedures. In the 27 patients who underwent brain tumor resection, white matter tract shifting ranged from an inward shift of 8 mm to an outward shift of 15 mm (mean shift +/- standard deviation, outward shift of 2.5 mm +/- 5.8). In 16 (59%) of 27 patients, outward shifting was detected; in eight (30%), inward shifting was detected. In eight patients who underwent temporal lobe resections for drug-resistant epilepsy, shifting was only inward and ranged from 2 to 14 mm (9 mm +/- 3.3). In two of the three patients who underwent burr hole procedures, outward shifting occurred. CONCLUSION: Intraoperative DTI can depict shifting of major white matter tracts that is caused by surgical intervention.

Adolescent↗
PubMed2004

Intraoperative high-field-strength MR imaging: implementation and experience in 200 patients.

PURPOSE: To review the initial clinical experience with intraoperative high-field-strength magnetic resonance (MR) imaging of brain lesions in 200 patients. MATERIALS AND METHODS: Two hundred patients (mean age, 46.1 years; range, 7-84 years), most of whom had glioma or pituitary adenoma, were examined with a 1.5-T MR imager equipped with a rotating operating table and located in a radiofrequency-shielded operating theater. A navigation microscope placed inside the 0.5-mT zone and used in combination with a ceiling-mounted navigation system enabled integrated microscope-based neuronavigation. The extent of resection depicted at intraoperative imaging, the surgical consequences of intraoperative imaging, and the clinical practicability of the operating room setup were analyzed. RESULTS: Seventy-seven resections with a transsphenoidal approach, 100 craniotomies, and 23 burr-hole procedures were performed. In 55 (27.5%) of 200 patients, intraoperative MR imaging had immediate surgical consequences (eg, extension of resection in 39% of patients with pituitary adenoma or glioma). In 108 patients the navigation system was used, and for 37 of those patients, functional imaging data were integrated into the navigation system. There was nearly no difference in quality between pre- and intraoperative images. Intraoperative workflow with intraoperative patient transport for imaging was straightforward, and imaging in most cases began less than 2 minutes after sterile covering of the surgical site. No complications resulted from high-field-strength MR imaging. CONCLUSION: The high-field-strength MR imager was successfully adapted for intraoperative use with the integrated neuronavigation system. Intraoperative MR imaging provided valuable information that allowed intraoperative modification of the surgical strategy.

Adenoma↗
PubMed2004

Strategies for brain shift evaluation.

For the analysis of the brain shift phenomenon different strategies were applied. In 32 glioma cases pre- and intraoperative MR datasets were acquired in order to evaluate the maximum displacement of the brain surface and the deep tumor margin. After rigid registration using the software of the neuronavigation system, a direct comparison was made with 2D- and 3D visualizations. As a result, a great variability of the brain shift was observed ranging up to 24 mm for cortical displacement and exceeding 3 mm for the deep tumor margin in 66% of all cases. Following intraoperative imaging the neuronavigation system was updated in eight cases providing reliable guidance. For a more comprehensive analysis a voxel-based nonlinear registration was applied. Aiming at improved speed of alignment we performed all interpolation operations with 3D texture mapping based on OpenGL functions supported in graphics hardware. Further acceleration was achieved with an adaptive refinement of the underlying control point grid focusing on the main deformation areas. For a quick overview the registered datasets were evaluated with different 3D visualization approaches. Finally, the results were compared to the initial measurements contributing to a better understanding of the brain shift phenomenon. Overall, the experiments clearly demonstrate that deformations of the brain surface and deeper brain structures are uncorrelated.

Brain Neoplasms↗
PubMed2004

Improved delineation of brain tumors: an automated method for segmentation based on pathologic changes of 1H-MRSI metabolites in gliomas.

In this study, we developed a method to improve the delineation of intrinsic brain tumors based on the changes in metabolism due to tumor infiltration. Proton magnetic resonance spectroscopic imaging ((1)H-MRSI) with a nominal voxel size of 0.45 cm(3) was used to investigate the spatial distribution of choline-containing compounds (Cho), creatine (Cr) and N-acetyl-aspartate (NAA) in brain tumors and normal brain. Ten patients with untreated gliomas were examined on a 1.5 T clinical scanner using a MRSI sequence with PRESS volume preselection. Metabolic maps of Cho, Cr, NAA and Cho/NAA ratios were calculated. Tumors were automatically segmented in the Cho/NAA images based on the assumption of Gaussian distribution of Cho/NAA values in normal brain using a limit for normal brain tissue of the mean + three times the standard deviation. Based on this threshold, an area was calculated which was delineated as pathologic tissue. This area was then compared to areas of hyperintense signal caused by the tumor in T2-weighted MRI, which were determined by a region growing algorithm in combination with visual inspection by two experienced clinicians. The area that was abnormal on (1)H-MRSI exceeded the area delineated via T2 signal changes in the tumor (mean difference 24%) in all cases. For verification of higher sensitivity of our spectroscopic imaging strategy we developed a method for coregistration of MRI and MRSI data sets. Integration of the biochemical information into a frameless stereotactic system allowed biopsy sampling from the brain areas that showed normal T2-weighted signal but abnormal (1)H-MRSI changes. The histological findings showed tumor infiltration ranging from about 4-17% in areas differentiated from normal tissue by (1)H-MRSI only. We conclude that high spatial resolution (1)H-MRSI (nominal voxel size = 0.45 cm(3)) in combination with our segmentation algorithm can improve delineation of tumor borders compared to routine MRI tumor diagnosis.

Adult↗
PubMed2004

Diagnosis and treatment of pituitary tumors.

PURPOSE OF REVIEW: Treatment of pituitary adenomas remains an interdisciplinary challenge involving neurosurgeons, endocrinologists and radiation oncologists. The different disciplines inaugurated advanced techniques to improve the already relatively high standard of outcome for the benefit of patients, covering molecular pathogenesis, novel therapeutic strategies for the different adenoma subtypes, developments in perioperative magnetic resonance imaging and radiosurgical management of pituitary adenomas. RECENT FINDINGS: Despite the progress achieved in medical treatment of hormone-secreting pituitary adenomas throughout recent years, surgery remains the primary therapy of choice except for prolactinomas. Recent studies in molecular pathogenesis aiming to find novel therapy targets and reports on new pharmacological drugs effecting GH-secreting pituitary adenomas are reviewed (for example, lanreotide 60, SOM320 and pegvisomant). Advances in surgical treatment of pituitary macroadenomas are obtained by pre- and especially by intraoperative (high-field) MRI offering a higher rate of safe and complete tumor removal. Therapy pitfalls mentioned in the literature throughout the last year as well as key points in the management of pituitary adenomas with focus on acromegaly and Cushing's disease are reported. Adjuvant irradiation for recurrent or residual adenomas is often a necessity. In comparison to standard conventional radiation strategies an increasing number of radiation oncologists and neurosurgeons report their experience with radiosurgery especially for smaller tumor remnants in pituitary adenomas. SUMMARY: Recent molecular studies suggest a new level of complexity in the tumorigenisis of pituitary adenomas in terms of possible cell-type-specific molecular changes. Except for prolactinomas surgery remains the primary treatment for pituitary adenomas. New pharmacological drugs achieve very encouraging endocrine results although no long-term follow-up is available so far. The results of trans-sphenoidal surgery will further improve by modern imaging techniques, especially by applying intraoperative high-field magnetic resonance imaging and neuronavigation. The results of radiosurgical techniques with regard to tumor control are mostly convincing, but definitive conclusions on long-term recurrence and/or late complications are not reliable so far.

Adenoma↗
PubMed2004

Volumetric assessment of glioma removal by intraoperative high-field magnetic resonance imaging.

OBJECTIVE: To investigate the contribution of high-field intraoperative magnetic resonance imaging (iMRI) for further reduction of tumor volume in glioma surgery. METHODS: From April 2002 to June 2003, 182 neurosurgical procedures were performed with a 1.5-T magnetic resonance system. Among patients who underwent these procedures, 47 patients with gliomas (14 with World Health Organization Grade I or II glioma, and 33 with World Health Organization Grade III or IV glioma) who underwent craniotomy were investigated retrospectively. Completeness of tumor resection and volumetric analysis were assessed with intraoperative imaging data. RESULTS: Surgical procedures were influenced by iMRI in 36.2% of operations, and surgery was continued to remove residual tumor. Additional further resection significantly reduced the percentage of final tumor volume compared with first iMRI scan (6.9% +/- 10.3% versus 21.4% +/- 13.8%; P < 0.001). Percentages of final tumor volume also were significantly reduced in both low-grade (10.3% +/- 11.5% versus 25.8% +/- 16.3%; P < 0.05) and high-grade gliomas (5.4% +/- 9.9% versus 19.5% +/- 13.0%; P < 0.001). Complete resection was achieved finally in 36.2% of all patients (low-grade, 57.1%; high-grade, 27.3%). Among the 17 patients in whom complete tumor resection was achieved, 7 complete resections (41.2%) were attributable to further tumor removal after iMRI. We did not encounter unexpected events attributable to high-field iMRI, and standard neurosurgical equipment could be used safely. CONCLUSION: Despite extended resections, introduction of high-field iMRI in conjunction with functional navigation did not translate into an increased risk of postoperative deficits. The use of high-field iMRI increased radicality in glioma surgery without additional morbidity.

Adolescent↗
PubMed2004

Frameless stereotactic surgery using intraoperative high-field magnetic resonance imaging.

This study evaluated the clinical validity of frameless stereotaxy using high-field intraoperative magnetic resonance (iMR) imaging combined with an in-room neuronavigation system. A 1.5 Tesla MR scanner in conjunction with a ceiling-mounted neuronavigation system was used during 32 frameless stereotaxy procedures consisting of 19 brain biopsies and 13 catheter placements between April 2002 and mid-October 2003. Evaluation of the procedure was based on either the rate of histological diagnostic yield or the ability to accurately position the catheter in the target region. This technique allowed successful registration with a mean error of 1.2 +/- 0.8 mm and resulted in successful placement of the instrument within the target tissue. Intraoperatively, frozen section analysis showed all biopsy samples contained pathological tissue and locations of sampling points were confirmed by iMR imaging. Specific final diagnosis was made in all 19 brain biopsies. The tip of the catheter was successfully placed into the target in all 13 patients confirmed by iMR imaging. The catheter was repositioned based on iMR imaging in four of 13 patients, increasing the rate of successful placement. There were no procedure-related neurological deficits or mortality, but we encountered two cases of wound infection, one needing surgical revision. Total additional procedure time related to the induction of iMR imaging was 76.7 +/- 23.3 minutes. This initial experience of the combination of conventional frameless stereotaxy and high-field iMR imaging improved the quality of frameless stereotaxy with low morbidity and mortality, but did not translate into a significant reduction of procedure-related time.

Adolescent↗
PubMed2004

Three-dimensional visualization of neurovascular relationships in the posterior fossa: technique and clinical application.

OBJECT: The goal of this study was to describe the authors' technique for three-dimensional (3D) visualization of neurovascular relationships in the posterior fossa at the surface of the brainstem. This technique is based on the processing of high-resolution magnetic resonance (MR) imaging data. The principles and technical details involved in the accurate simultaneous visualization of vessels and cranial nerves as tiny structures are presented using explicit and implicit segmentation as well as volume rendering. METHODS: In this approach 3D MR constructive interference in steady state imaging data served as the source for image processing, which was performed using the Linux-based software tools SegMed for segmentation and Qvis for volume rendering. A sequence of filtering operations (including noise reduction and closing) and other software tools such as volume growing are used for a semiautomatic coarse segmentation. The subsequent 3D visualization in which implicit segmentation is used for the differentiation of cranial nerves, vessels, and brainstem is achieved by allocating opacity and color values and adjusting the related transfer functions. This method was applied to the presurgical evaluation in a consecutive series of 55 patients with neurovascular compression syndromes and the results were correlated to surgical findings. The potential for its use, further developments, and remaining problems are discussed. CONCLUSIONS: This method provides an excellent intraoperative real-time virtual view of difficult anatomical relationships.

Brain Stem↗